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Nuclear DNA is a nucleic acid, a polymeric biomolecule or biopolymer, found in the nucleus of eukaryotic cells.Its structure is a double helix, with two strands wound around each other, a structure first described by Francis Crick and James D. Watson (1953) using data collected by Rosalind Franklin.
Deoxyribonucleic acid (DNA) is a nucleic acid containing the genetic instructions used in the development and functioning of all known living organisms. The chemical DNA was discovered in 1869, but its role in genetic inheritance was not demonstrated until 1943. The DNA segments that carry this genetic information are called genes.
Three sequences, UAG, UGA, and UAA, known as stop codons, [note 1] do not code for an amino acid but instead signal the release of the nascent polypeptide from the ribosome. [7] In the standard code, the sequence AUG—read as methionine—can serve as a start codon and, along with sequences such as an initiation factor, initiates translation.
DNA exists in many possible conformations that include A-DNA, B-DNA, and Z-DNA forms, although only B-DNA and Z-DNA have been directly observed in functional organisms. [14] The conformation that DNA adopts depends on the hydration level, DNA sequence, the amount and direction of supercoiling, chemical modifications of the bases, the type and ...
In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape that the nucleic acid assumes. The bases in the DNA are classified as purines and pyrimidines. The purines are adenine and guanine ...
Before this loss, DNA methylation allows the adequate expansion of the genome. [30] In humans, the nuclear genome comprises approximately 3.1 billion nucleotides of DNA, divided into 24 linear molecules, the shortest 45 000 000 nucleotides in length and the longest 248 000 000 nucleotides, each contained in a different chromosome. [45]
DNA uses T instead. This mRNA molecule will instruct a ribosome to synthesize a protein according to this code. The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets or codons ) into proteins .
Deoxyribonucleic acid (DNA) is a nucleic acid which carries genetic instructions for the biological development of all cellular forms of life and many viruses The main article for this category is DNA .